Railway transportation plays a big part in urban transportation. In order to ensure safe running of the railway transportation, a higher requirement is put forward for quality of wheels. In order to prevent a defective wheel from causing an accident during running, and ensure driving safety of a train, it is required to perform defect detection for a tread, a wheel rim, a spoke, and other parts of the wheel. Meanwhile, it is hoped to perform on-line detection (defect detection) without disassembling a wheel set.
Major causes of a wheel defect include: during smelting and processing of steel used for the wheel, some defects such as gas holes, blisters, inclusions, and scratches are often generated on a surface of the wheel or inside the wheel. Because of existence of these defects, stress concentration may be caused during running of the wheel. In an area of stress concentration, a bearing capacity of metal is small, cracks are prone to extend; under a situation of continuous bearing, the cracks continuously expands, and exfoliation and chipping are generated on the surface of the wheel. In severe cases, risks of wheel “collapsing” or axle breakage may be caused.
Currently, an effective method is an ultrasonic defect inspection method, such as a piezoelectric ultrasonic defect inspection method. A principle thereof is that: if a wheel has a defect such as a gas hole, a crack, and layering (there is air in the defect), when being broadcast to an interface of the defect, an ultrasonic wave may be entirely or partially reflected, the reflected ultrasonic wave is received by a probe, and a depth, a position, and a shape of the defect of a workpiece may be determined according to change features of a waveform.
However, when the ultrasonic defect detection is used, it is required to ensure that an air gap between an ultrasonic probe and the detected wheel is filled with fluid, such as water. Therefore, the wheel is usually separated from a locomotive, and then is placed in water, and the ultrasonic probe is placed in the water to perform detection. It is very difficult to have an overall check on the wheel without separating the wheel from the locomotive.
Therefore, it is necessary to provide an improved system and method to solve the foregoing technical problem.